Final Thesis

 
 
 
 
 
 
 
 
 

---

TAMK University of Applied Sciences 
Escola Politécnica Superior de Castelldefels 
Marcos Tejedor Alonso 
8 (44) 
1.Introduction to Digital TV 
 
1.1 The digitization process 
In the beginning of the 80's the digital era started and a lot of companies began to develop digital systems. 
One of the main challenges was to the digitization of television. This one was divided in two different parts. 
On one side was the digitization of production and on the other side the digitization of transmission. 
The digitization of production developed many systems. The first one were based on digitizing composite 
video signal without success. The video signal is composed by luminance and colour difference and 
digitization of each signal separately of the other was the most suitable. 
It was originally developed signalizing the signals in parallel, with thick cables that needed one for each bit, 
but was soon replaced by the time multiplexed transmission of each of the signal's components. This system 
also allowed to include audio, included in the information that is transmitted, and other utilities that make it 
perfect to develop the digital TV. 
Another challenge was the maintenance of the quality needed for TV production that is higher than the 
transmission. For this reason was developed the Studio Quality standard CCIR-601. Also appears standards 
for another fields that were less demanding (electronic news and light production). 
The difference between the production quality in the studio and the fields less demanding is in the binary 
stream generated in the digitization of the signals, that is more higher in the first one.
The reduction of bits that were needed allowed to use algorithms, all based on discrete cosine transform 
used in the spatial and time domain, that reduced the flow making possible the construction of more 
affordable equipment . This opened the way for the small production companies and TV broadcasting and 
was the rise of local television. 
For the transmission, digitization was possible by compression techniques that succeeded in reducing the 
flow from 270Mbit/s (original flow of a studio quality) to less than 5 Mbit/s. This compression is called MPEG-
2 
and 
produced 
streams 
between 
4 
and 
6 
Mbit/s 
without 
significant 
losses. 
[1]